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LEDs’ potential to save our night skies

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Re: LEDs’ potential to save our night skies

#161

Post by yodsanklai »

anal_reactor wrote: post #151
uv-depression wrote: post #25

Greenhouses here in the lower mainland of British Columbia have been devastating to the night sky. It's quite depressing how little society values the night sky, something that's been an important part of every human culture for longer than recorded history. I've taken friends out to thoroughly mediocre skies (Bortle 4-5) and they've been very impressed, because they're used to city lights (Bortle 9) where you can ma…

Are there places in EU that are dark and easy to visit?

In the EU, the canary islands are known to have great skies. You check this map https://www.lightpollutionmap.info

I've been in some place with very dark skies, like Death Valley or Teide in the Canaries (https://www.teidebynight.com/tenerifes-dark-sky-reserves-hav...). It was great, but also not that much better than what I've seen closer to home in French countryside or in the alps. Maybe I didn't get the best conditions though.

Re: LEDs’ potential to save our night skies

#162

Post by t-3 »

oblio wrote: post #119
qurren wrote: post #105

Earlier quoted context omitted.

Some good points. However: > replacing the majority of air travel with high speed rail I absolutely LOVE high speed rail, but I will note that it is correlated with far more light pollution than air traffic. I say correlated because typically high speed rail is routed through high-density population centers, but if there aren't population centers, you'll have to have plans to create them in order to support the rail…

> but if there aren't population centers, you'll have to have plans to create them in order to support the rail system itself. This is such a misanthropic point of view. Nobody "creates" population centers. People aren't created out of raw clay, they already exist. If population centers are "created" it's because people already exist and want to live in a specific place, often time urban. And if they wouldn't go to t…

Many cities and settlements have been created intentionally rather than as a result of populations organically reproducing on the spot. Colonies, chartered towns/cities/etc, company towns, etc. It's a very common thing throughout history to the present day.

Re: LEDs’ potential to save our night skies

#163

Post by [deleted] »

amiga386 wrote: post #36
trollbridge wrote: post #19

Earlier quoted context omitted.

Wouldn't it be more reasonable to just expect people who want to walk places in the dead of night to wear a headlamp? They're cheap, easy to recharge, and can be adjusted for various brightness levels.

The problem is not just with people who want to walk places, but people who want to mug/murder/rape those that do. As an example, in the UK, councils are expected to light commonly-traveled paths, both so path users can see where they're going, and to reduce crime. Unlit paths in city parks are still traversed, and are often a haven for crime. "Dead of night" isn't the right image. 5PM in winter with clouds (as is ty…

[deleted]

Re: LEDs’ potential to save our night skies

#164

Post by amiga386 »

naravara wrote: post #45
amiga386 wrote: post #36

Earlier quoted context omitted.

The problem is not just with people who want to walk places, but people who want to mug/murder/rape those that do. As an example, in the UK, councils are expected to light commonly-traveled paths, both so path users can see where they're going, and to reduce crime. Unlit paths in city parks are still traversed, and are often a haven for crime. "Dead of night" isn't the right image. 5PM in winter with clouds (as is ty…

> The problem is not just with people who want to walk places, but people who want to mug/murder/rape those that do. This is a completely irrational (though commonplace) fear. Criminals aren’t hiding out in bushes in desolate parks to mug or rape random people. Muggings most commonly happen in side paths off of busy high streets because criminals, being people, like to hang out in stimulating places where they won’t…

> desolate parks

Criminals hide out in the dark parts of urban parks, mere minutes away from well-lit, more populated areas of the city. They're not going to get bored. Victims walk through the parks and get jumped, occasionally dragged off into the darker parts.

To give a example: The Meadows in Edinburgh: https://www.openstreetmap.org/way/233760765

A park between the university and student accomodation. Very popular with students going home at night. Apart from a few lit paths, entirely dark. Most paths are lined with trees, like so: https://www.edinburghnews.scotsman.com/webimg/b25lY21zOjAxYz...

Here's a small sample of incidents. There are genuinely criminals who hang about in the dark parts of this park, late at night, in order to attack victims. They don't have to wear ghille suits, they need only stand behind the trees.

- 2011: https://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-1... "Two men who grabbed a young woman before one sexually assaulted her in an Edinburgh park are being sought by police. The 19-year-old woman was walking through the Meadows at 03:30 on Tuesday when she was attacked at a spot north of Melville Drive."

- 2011: https://www.scotsman.com/news/charges-over-sex-assaults-in-m... "Lothian and Borders Police issued an open letter to students and residents in response to the incidents, advising them not to walk alone in the Meadows at night"

- 2012: https://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-2... "The 30-year-old was walking through Middle Meadow Walk at about 22:30 when two men approached him. One of the men punched the victim in the face, knocked him to the ground and continued assaulting him before taking his personal belongings."

- 2014: https://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-2... "The 25-year-old was walking near the tennis courts at the east end of the park at about 04:30 on Saturday when he was approached by two men. After asking the man for money, the two attackers punched him several times, causing minor facial injuries, and also tried to steal his watch."

- 2014: https://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-3... "Steven Davidson, 24, attacked the 19-year old as she made her way home through the Meadows in November 2014. [...] Davidson ran up and grabbed her from behind. [...] The woman had been making her way home just before 07:00 [...] she passed out and came round to find him lying on top of her. He then raped her."

- 2016: https://archive.news.stv.tv/east-central/1374940-three-assau... "Police are investigating after three assaults were carried out on the Meadows in Edinburgh within 15 minutes of each other. In each of the incidents, which took place between 3.10am and 3.25am on Sunday, the attackers robbed or attempted to rob the victims of cash or possessions."

- 2020: https://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-5... "The attack on the 37-year-old took place on The Meadows at about 23:15 on Saturday"

- 2023: https://www.edinburghlive.co.uk/news/edinburgh-news/edinburg... "The incident took place at around 4am on Sunday, January 29."

I'm not saying we should floodlight the park. What has helped most is regular police patrols of the park. But I'd be lying if I said the criminals don't hang out in the dark parts of this park, waiting for victims. They do.

Re: LEDs’ potential to save our night skies

#165

Post by thayne »

esikich wrote: post #158
NooneAtAll3 wrote: post #150

Earlier quoted context omitted.

> They are only visible when they are spinning up to orbit > and are extremely easy to remove with the most basic of outlier rejection techniques; netizens often amplifiy outliers by max-stacking instead of outlier-rejected mean-stacking to make Starlink look much worse than it is my understanding was that they are a problem on much bigger scale than yours "one dude with mobile telescope (or maybe just a camera?)" su…

I don't see how this can be true especially if you have a fancy telescope tracking something, take 3-5 whatever many shots in succession and stack. It's astrophotography 101.

For professional astronomers, it really sucks if you only have, say, an hour of observing time on a big telescope, and then a few of your precious frames are ruined because of a satellite. And you don't always even know that the frame is ruined until later, or have the flexibility to take more frames if needed (because you submit the full observation plan ahead of time, and just get the results later), in which case one bad frame can mean you don't have enough good frames to get valuable data.

Or more generally, let's say 10% of frames have satellite noise. That means there is 10% less observing you can do in a night. For amateurs, that is annoying. For professionals, that means less science can be done.

Re: LEDs’ potential to save our night skies

#166

Post by groos »

I read through most of the article but didn't see motion sensors mentioned. A lot of suburban streetlights are lighting up empty streets at night. With a combination of motion sensing and LEDs, lighting could follow pedestrians. Cars really don't need street lights in most cases but even then, in higher risk areas, motion sensors could turn on streetlights just as long as needed.

Re: LEDs’ potential to save our night skies

#167

Post by wffurr »

groos wrote: post #166

I read through most of the article but didn't see motion sensors mentioned. A lot of suburban streetlights are lighting up empty streets at night. With a combination of motion sensing and LEDs, lighting could follow pedestrians. Cars really don't need street lights in most cases but even then, in higher risk areas, motion sensors could turn on streetlights just as long as needed.

A motion sensor activated light unpredictably turning off and on on my street would be worse than the steady street lamps we have now. It would be even more distracting and annoying.

Re: LEDs’ potential to save our night skies

#168

Post by thayne »

I'm surprised it didn't suggest using red LEDs without phosphorescence, which has several advantages:

1. Red light preserves your dark adaptation

2. It doesn't have as much of an impact on your circadian rythm

3. Not using phosphorescence can increase the lifetime of the light, since you don't have to worry about the coating degrading

4. Red light is less energetic, so could potentially use less power.

5. Since an LED without phosphorescence is a single wavelength, telescopes (and binoculars) can use a narrow band filter to filter out the light pollution, without blocking most of the light from celestial objects.

Re: LEDs’ potential to save our night skies

#169

Post by esikich »

thayne wrote: post #165
esikich wrote: post #158

Earlier quoted context omitted.

I don't see how this can be true especially if you have a fancy telescope tracking something, take 3-5 whatever many shots in succession and stack. It's astrophotography 101.

For professional astronomers, it really sucks if you only have, say, an hour of observing time on a big telescope, and then a few of your precious frames are ruined because of a satellite. And you don't always even know that the frame is ruined until later, or have the flexibility to take more frames if needed (because you submit the full observation plan ahead of time, and just get the results later), in which case…

That's what I don't understand, how are they ruined? If you're so deep that you need minutes or hours of exposures, that satellite will blip past the frame so fast it's not going to matter. And if the exposure time is less than that, you stack.

Re: LEDs’ potential to save our night skies

#170

Post by dwoosley »

> “… gives the illusion, without the reality, of safety”

This actually isn’t true. Having done physical security work before, a weird fact is that one of the best physical deterrents is lighting; even over CCTV.

I don’t say that to take away from this, this is great work and I’d love to see the lighting toned down for multiple reasons. However, this should be framed as a security tradeoff not an outright win.

Source: The Impact and Policy Relevance of Street Lighting for Crime Prevention: A Systematic Review Based on a Half-Century of Evaluation Research (https://www.crimrxiv.com/pub/wl9zqxga/release/1)

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